add validation for stream=False with yield usage

[aniketmaurya]

What does this PR do?

This PR, protects users from making mistake before starting the server and removes a redundant code.

Before submitting

• Was this discussed/agreed via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

PR review

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[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 89%. Comparing base (e9b1ee1) to head (0eb4388).
Report is 1 commits behind head on main.

Additional details and impacted files

@@         Coverage Diff         @@
##           main   #402   +/-   ##
===================================
- Coverage    89%    89%   -0%     
===================================
  Files        30     30           
  Lines      1902   1893    -9     
===================================
- Hits       1692   1683    -9     
  Misses      210    210